You need to correct Read & Write Permission to following Adobe folders.
(Mac Library) /Library/Application Support/Adobe
(User Library) ~//Library/Application Support/Adobe
cmd+click on Adobe folder<< Click on Get info
Go to Sharing & Permission
Change the Permission for all users to Read & Write.
Let us know if that helps.
all users say read and write
still no dice
If you check, there's "+" mark at the bottom on that windows to add more user's
Click on it and Add the Administrator, your user to the both location and give Read & Write Permission
Restart Machine and try Lightroom.